(1) Field of the Invention
The present invention relates to an improved method of manufacturing depressed center abrasive wheels having a thickness of less than three thirty seconds (3/32) of an inch. Such wheels are called type 27 cut off wheels.
(2) Description of Prior Art
Depressed center type 27 cutting wheels are currently manufactured by a process that provides for layers of grit or grain in a resin mixture with fiberglass reinforcement mats provided in a cavity having the general profile of the final depressed center shape of the wheel. After such lay-up is prepared in the cavity, the lay-up is compressed so that the center and outer portions of the wheel must be successively formed to provide a depressed center wheel in the "green" state.
A stack of like wheels are then provided between metal plates for transfer to an oven to cure the "green" wheels.
Depressed center resin-type cutting wheels of this general character have been restricted in thickness because this pressing operation of forming a depressed center wheel in the "green" state, causes the resin mixtures and the fiberglass to be pulled toward the center of the wheel, causing the wheel to lose total uniformity or homogeneity throughout the lay-up. This problem has resulted in the thickness of such type 27 depressed center cutting wheels being limited to more than three thirty-seconds of an inch in thickness. Depressed center wheels of less than 3/32 of an inch are adversely affected by this conventional process of making such wheels. The present invention relates to fulfilling the need for type 27 depressed center resin-type wheels of less than 3/32 of an inch in thickness.